Is SodaStream Getting Frothy?

Revenues are pouring in at the seltzer-machine company, but the stock price reflects that growth, and more.

Correction: A previous version of this story mistakenly asserted that the company that acquired SodaStream in 1998 had also taken it public.

SodaStream shares have jumped 30% in a month, to about $45. At 21 times this year's earnings forecast, it's a pricey stock -- but not so pricey that investors should bet against it. Some 60% of the shares available for trading had been sold short as of the end of November. Those traders are...